SHALLOW- WATER STARFISHES 125 



Interactinal spines are similar to the inferomarginals and form 

 three simple oblique rows proximally, one spine to a plate, there 

 being three rows of small, thick interactinal ossicles separated by 

 rows of small papular pores. The peractinal row reaches nearly to 

 the tip of the ray ; the next one reaches to about the middle ; while 

 the third is confined to the basal part of the ray. All these rows bend 

 upward pretty regularly proximally. 



Adambulacral spines slender, tapered, obtuse, much smaller and 

 shorter than the interactinals, subdiplacanthid, part of the plates 

 bearing one, and part two spines in irregular alternations. Oral 

 spines have been destroyed in the type. 



Small wreaths of minute minor pedicellariae surround most of the 

 dorsal spines ; major pedicellarise few and small. Madreporite small, 

 fine-grained, surrounded by a circle of small clavate spinules. 



The type was taken at Departure Bay, Vancouver Island, on rocks 

 at low tide by Prof. John Macoun and party, of the Canadian Geo- 

 logical Survey, 1909 (No. 43). It is dedicated to Prof. John Ma- 

 coun. I have seen no others. 



This species most resembles L. hexactis in general appearance, but 

 the latter has the dorsal spines clustered and has fewer rows of 

 actinal plates and spines. It may eventually prove to be a variety of 

 hexactis, when a larger series can be studied. I have seen no inter- 

 mediate specimens. 



LEPTASTERIAS VANCOUVERI (Perrier). 



Asterias Vancouver* PERRIER, Arch, de Zool. Exper., iv, p. 328, 1875. Bell, 

 Trans. Zool. Soc. London, pp. 496, 504, 1881. t A hexactis Stimpson. 



No specimen perfectly agreeing with this small diplacanthid 

 species has come under my observation. 



According to the imperfect description of M. Perrier, it somewhat 

 resembles, in form and ornamentation, Asterias (Stichaster) poly- 

 plax. Arms six or seven. Adambulacral spines long, pointed, two 

 upon each plate, but not in two regular rows, the rows irregularly al- 

 ternating ; each bears on the middle one or two small major pedicel- 

 larise. Outside of these are two rows of pointed ventral spines, larger 

 than the adambulacrals and surrounded by a few minor pedicel- 

 lariae. Ossicles of the dorsal skeleton much as in ordinary species of 

 Asterias. On the back are five ranges of groups of small obtuse 

 spines, each ossicle bearing a group of three or four spines ; other 

 spines are borne on the transverse connecting ossicles, so that the 

 groups of spines appear confluent and form a vague reticulation. 



